At least one of the seals had suffered blood loss and seemed to have died while trying to free fishing net wrapped tightly around its mouth. The other mammals may, at some stage, have been entangled in nets.

Local woman Helen Russell was walking her two dogs on the beach when she spotted what she first thought was a rock.

“Then I saw it was a dead young seal with wire around its mouth,” she said. “It was bone-crushingly sad to see such a beautiful creature in that state.”

The dead porpoise discovered in west Waterford

She discovered the porpoise dead some 15 metres away. Three more dead creatures were later discovered in the vicinity. The finds come as the mid-water pair-trawling fleet join local boats in chasing herring in the Celtic Sea which stretches the length of the south coast.

Large numbers of seals, dolphins and fin whales were spotted off Ardmore in recent days. Humpback whales are also off the south coast in big numbers.

One local said the discovery sparked “considerable comment” but local fishermen regularly find their nets raided by seals and dolphins.

One of the four dead seals washed up at Ardmore Beach.

Although the washing up of several species within 24 hours is a remarkable coincidence, it is believed the deaths were accidental and probably caused by close encounters between the dead mammals and pair-trawlers.

Organisations such as the Irish Whale and Dolphin Society have regularly highlighted the bycatch risks of fishing techniques such as pair trawling which lead to indiscriminate deaths of non-targeted species such as those found on Ardmore beach.